In a way, they are offering a better life; just one that is so far removed from this society that its basically their equivalent to "heaven."

Many of them truly believe if they remove all the wrong thinkers, adopt communism, and "choose kindness" they will create a magical perfect utopia that is probably identical to most other religion's idea of heaven. Except its here on Earth. They will die and sacrifice anything to get there, the same way many would do the same for their religious afterlife.

The problem being that "on Earth" detail. Which means its bound by the restrictions of things we can actively observe and understand, and that's how we know its impossible, retarded, and every other negative label.